The patch titled
Subject: mm: compaction: check lock contention first before taking lock
has been added to the -mm tree. Its filename is
mm-compaction-check-lock-contention-first-before-taking-lock.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Shaohua Li <shli@xxxxxxxxxx>
Subject: mm: compaction: check lock contention first before taking lock
isolate_migratepages_range will take zone->lru_lock first and check if the
lock is contented, if yes, it will release the lock. This isn't
efficient. If the lock is truly contented, a lock/unlock pair will
increase the lock contention. We'd better check if the lock is contended
first. compact_trylock_irqsave perfectly meets the requirement.
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/compaction.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff -puN mm/compaction.c~mm-compaction-check-lock-contention-first-before-taking-lock mm/compaction.c
--- a/mm/compaction.c~mm-compaction-check-lock-contention-first-before-taking-lock
+++ a/mm/compaction.c
@@ -349,8 +349,9 @@ isolate_migratepages_range(struct zone *
/* Time to isolate some pages for migration */
cond_resched();
- spin_lock_irqsave(&zone->lru_lock, flags);
- locked = true;
+ locked = compact_trylock_irqsave(&zone->lru_lock, &flags, cc);
+ if (!locked)
+ return 0;
for (; low_pfn < end_pfn; low_pfn++) {
struct page *page;
_
Patches currently in -mm which might be from shli@xxxxxxxxxx are
linux-next.patch
readahead-fault-retry-breaks-mmap-file-read-random-detection.patch
swap-add-a-simple-detector-for-inappropriate-swapin-readahead.patch
swap-add-a-simple-detector-for-inappropriate-swapin-readahead-fix.patch
mm-compaction-abort-compaction-loop-if-lock-is-contended-or-run-too-long.patch
mm-compaction-check-lock-contention-first-before-taking-lock.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
